Vacuum-operated timing device with solenoid-closable vent in valve chamber

ABSTRACT

A timing device having a vacuum chamber enclosing a diaphragm which is mechanically connected to a switch in an electric circuit. The vacuum chamber is connected to a source of vacuum through a port controlled by a check valve and also through an adjustable restricted passage which bypasses the port. When vacuum at the source drops below a predetermined level, air is evacuated from the chamber after a delay determined by the selected size of the restricted passage. A vent in the valve chamber wall normally is open to atmosphere and the circuit includes a control device which closes the vent when the circuit is energized.

United States Patent Jordan et al.

[54] VACUUM-OPERATED TIMING DEVICE WITH SOLENOID-CLOSABLE VENT IN VALVECHAMBER [72] Inventors: Leslie H. Jordan, 2021 East Broadway, Vancouver,British Columbia; John Arden, 6049 Portland Ave., Burnaby, BritishColumbia, both of Canada {22] Filed: Nov.9,l970

[21] Appl. No.: 88,060

[ 1 Feb. 1, 1972 Long ..200/34 Jordan et al ..200/83 R [5 7] ABSTRACT Atiming device having a vacuum chamber enclosing a diaphragm which ismechanically connected to a switch in an electric circuit. The vacuumchamber is connected to a source of vacuum through a port controlled bya checkvalve and also through an adjustable restricted passage whichbypasses the port. When vacuum at the source drops below a predeterminedlevel, air is evacuated from the chamber after a delay determined by theselected size of the restricted passage. A vent in the valve chamberwall normally is open to atmosphere and the circuit includes a controldevice which closes the vent when the circuit is energized.

2 Claims, 5 Drawing Figures rmmtnm um 3.639.711

i I2 107A, 60A4 24 INVENTCR5 LESLIE H. JORDAN JOHN ARDEN W J 23. ATORNEY VACUUM-OPERATED TIMING DEVICE WITII SOLENOID-CLOSABLE VENT INVALVE CHAMBER Our invention relates to improvements in a vacuumoperated, delayed action timing device for controlling an electriccircuit.

In our US. Pat. No. 3,466,410 issued Sept. 9, 1969, we disclosed avacuum operated timer switch arrangement which is particularly intendedfor use in operating warning lights at the rear of a car. The purpose ofsuch lights is to warn the drivers of following cars that the vehicleequipped with the warning lights is slowing down. The timer switch ofour prior patent was shown, by way of example, operating in conjunctionwith a second vacuum operated speed change indicator switch as describedin our prior US. Pat. No. 3,363,075 issued on Jan. 9, l968. Both theseswitches were shown connected to a common source of vacuum, in thisinstance, the intake manifold of a car. Whenever the vehicle so equippeddecelerates and a predetermined level of vacuum is developed in theintake manifold, the indicator switch operates to close the warninglight circuit. Should the car be descending a long hill, the operatinglevel of vacuum will be maintained for a lengthy period and this wouldkeep the warning lights which might confuse the drivers of the followingcars as to whether the leading car was actually slowing down or merelyproceeding at a constant but slower speed. This was intended to beremedied by the timer switch which, after a suitable delay, opens thecircuit previously closed by the speed change indicator switch.

Such an arrangement of switches works well under nearly allcircumstances with one possible exception. It may happen that thevehicle so equipped has been running at or near idling speed for alengthy period immediately prior to descending the long hill. As aresult, the vacuum chamber of the timer switch will be evacuated ofnearly all its air and therefore the switch will be open and the circuitbroken. If the car then starts to descent the long hill and builds upspeed even at a low throttle setting, the driver will take his foot offthe accelerator but the rear warning lights will not come on since thecircuit is broken by the timer switch. This difficulty can be overcomeif the driver will accelerate so as to recharge the vacuum chamber withair but, since a car is already accelerating on the hill, he probablywill not want to increase his speed still further.

Our improved vacuum operated timing device corrects this small butimportant defect found in our earlier switch arrangement by providing avalve chamber which has a normally open vent to atmosphere. Thus thechamber cannot be evacuated during periods when the engine is run at lowspeeds. The device has control means for closing the normally open vent,the means operatingautomatically the moment the indicator switchis'actuated to close the circuit. An adjustment on the device enablesthe timed interval of its operation to be adjusted and because thecontrol means acts instantly as described, this time interval is notextended and a particularly precise degree of control is then madepossible.

In drawings which illustrate a preferred embodiment of the invention,

FIG. 1 is a side elevation of a vacuum controlled timing device,

FIG. 2 is an enlarged horizontal section taken on the line 2-2 of FIG.I, I

FIG. 3 is a schematic view of a metering screw,

FIG. 4 is a transverse section taken on the line 4-4 of FIG. 2, and

FIG. 5 is a wiring diagram showing the timing device in a typicalcondition of use.

Referring to the drawings the numeral indicates generally a timingdevice which is shown to comprise a vacuum unit 12, switch means 14, andcontrol means 16. The device 10 conveniently can be mounted on abaseplate 17, the unit 12 which carries the switch means 14 beingprovided with a transversely extending mounting stand 18, and thecontrol means 16 being supported by a bracket 19.

As shown best in FIG. 2, the vacuum unit 12 comprises a casing 24 whichhas a cylindrical wall 25, a left end wall 26, a

right end closure 27, with a vacuum chamber 28 being definedtherebetween. A diaphragm 30 is clamped between the cylindrical wall 25and the end closure 27 to extend across the vacuum chamber 28 and sealoff that end of the unit. Diaphragm 30 is secured to a centrallydisposed stem 31 by means of a cup 32 and a clamping nut 33. Theinwardly projecting end wall 26 of the casing is shaped to provide abearing 37 in which the inner end of the stem 31 is slidably mounted. Acompression spring 38 is interposed between the bearing 37 and the cup32 to urge the diaphragm 30 towards the end closure 27. In FIGS. 3 and4, it will be noted the bearing 37 is provided with a number oflongitudinally extending passages 39 which allow air to pass betweensaid bearing and stem 31.

To the left of the bearing 37.(FIG. 2) the end wall 26 is counterboredto provide a valve chamber 42 and a recess 43. The recess 43 houses anadapter 45 having a cylindrical head 46 and an outwardly projecting tube47. Head 46 is suitably secured against withdrawal from the recess 43and the inner face of said head is shaped to provide a valve seat 50 anda port 51. Tube 47 has a bore 52 which communicates with the port 51. Adisc-type check valve 54 is held against the seat 50 by a compressionspring 55, this spring butting against the inner end of the bearing 37.The head 46 is provided with a peripheral groove 57 as well as with aradial aperture 58 which connects said groove to the port 51.

The casing end wall 26 is drilled to provide a restricted passage 60having portions 60A and 608, which passage places vacuum chamber 28 incommunication with port 51 through the groove 57 and aperture 58. Ametering screw 63 is threaded into the enlarged portion 60A of therestricted passage 60, the screw being locked into adjusted position bymeans of a nut 64. The threads on the screw 63 and/or the mating threadswithin portion 60A of the restricted passage 60 are shaped to provide aclearance which progressively increases towards the tip of said screw.As shown schematically in FIG. 3, this clearance is provided by removingthe crests of the internal threads so that these threads taper inwardlyto a slight extent. This provides a clearance indicated by the letter Aand this clearance is exaggerated in FIG. 3 for purposes ofillustration. Thus, when the meter screw 63 is advanced, it serves torestrict the passage 60 and when retracted, the amount of restriction iscorrespondingly reduced. This arrangement provides a much finer degreeof adjustment than could be achieved by a conventional needle valve forexample.

The switch means generally indicated at 14 is shown in FIG. 2 tocomprise a normally closed microswitch 70 which is mounted on a bracket71 carried by the casing 24 for swinging movement about a vertical pivotpin 72. An extension 73 of switch 70 is provided with an arcuate slot 74and the bracket 71 has a locking screw 75 which projects upwardlythrough this slot. Switch 70 has a spring-pressed operating plunger 77.A leaf spring 78 is carried by switch 70 to extend across the plunger77, the free end of said spring being engaged by outer end 79 of thediaphragm stem 31.

The cylindrical wall 25 of the vacuum unit 12 is provided with a vent 84which connects the vacuum chamber 28 to atmosphere and this vent isadapted to be opened and closed by the means 16 of the present timingdevice. In FIG. 2, the vent control means generally indicated at 16 isshown to comprise a solenoid 86 which is mounted within a substantiallyU-shaped frame 87, the frame being suitably secured to the bracket 19.Mounted on the frame 87 for rocking movement about a vertical pivot 89is an armature 90 which extends alongside the casing 24 of the unit 12.One end of the armature 90 is positioned over the solenoid 86 and theopposite end thereof is fitted with a stopper pad 92 which is alignedwith the vent 84. A tension spring 93 is connected to the armature 90and the frame 87 normally to hold the stopper pad 92 off the casing 24so that the vent 84 remains open.

Referring now to FIG. 5, this diagram shows the timing device 10connected into a series circuit generally indicated at 101 whereby tocontrol the operation of a pair of rear warning lights 102. For thispurpose, the circuit 101 would include the battery 103 of the vehicleand may also be provided with a flasher 104 to operate the lights 102intermittently. The timing device 10 is connected by the circuit 101 toa normally open speed change indicator switch indicated generally at 106and shown diagrammatically in FIG. 5 only. Switch 106 is thevacuum-operated vehicle speed change indicator switch described indetail in our U.S. Pat. No. 3,363,075. Switch 106 is connected by alength of hose 107 to a source of vacuum, which in this instance, is theintake manifold (not shown) of the vehicle. A branch 107A of the hose107 extends to the timing device and is connected to the tube 47 of theadapter 45 as shown best in FIG. 2.

The normally closed microswitch 70 is adjusted to select a predeterminedlevel of vacuum at which said switch will operate. To carry out such anadjustment, the screw 75 is backed off a few turns and the microswitch70 is swung about the pivot pin 72 to dispose said switch at a suitableangle relative to the end closure 27, whereupon the locking screw 75 isagain tightened. At this time, the leaf spring 78 is in contact with theend 79 of the stem and continues to hold the plunger 77 in closedposition. lt is then necessary for the stem 31 to move a selecteddistance before the microswitch 70 will open. To bring about therequired movement of the stem 31, the diaphragm 30 must flex acorresponding distance and this distance is determined by the level ofvacuum within the chamber 28. Thus, it is possible to set the timingdevice 10 so that it will respond only to a predetermined level ofvacuum. This vacuum level normally is quite high to ensure that themicroswitch 70 is not operated by minor fluctuations in the level ofvacuum.

The metering screw 63 is also adjusted as required to control the lengthof time needed to evacuate the chamber 28 through the restricted passage60. When the screw 63 is advanced as far as it will go into the passage60, only a very slight clearance is provided between the male and femalethreads of these two parts. This reduces the restricted passage 60 to aminimum with a result that quite a long time is required to evacuate thechamber 28. By backing off the screw 63 a partial turn, the clearancebetween the threads can be increased very slightly and the periodrequired for air within the chamber 28 to flow through the restrictedpassage 60 is shortened accordingly. Thus, the period of delay beforewhich the switch 70 will open is readily controlled within extremelyfine limits by means of the metering screw 63.

Assuming the vehicle fitted with the assembly shown in FIG.

.5 is moving along the road, the driver occasionally will lift his footoff the accelerator to cause a buildup of vacuum in the intake manifold.If the manifold vacuum rises to a predetermined level, switch 106 isactuated to cause the warning lights 102 to go on. This warns the driverof a following car that the leadingcar is decelerating so that he canadjust his speed accordingly. When the accelerator of the leadingvehicle is again depressed, the vacuum drops below the predeterminedlevel and the switch 106 opens to turn off the lights 102. Thus, therear warning lights are operated solely by the switch 106 at this time.

' However, if the car is descending a long hill, the high level ofvacuum will be maintained for a sufficiently long period to bring thetiming device 10 into operation as well as the switch 106. The indicatorswitch 106 operates as described above to close the circuit 101 and, atthe same time, completes the aforesaid series circuit to energize thesolenoid 86 and close the vent 84. Thus a volume of air is trappedwithin the chamber 28 and must be evacuated therefrom before thenormally closed switch means 14 will open. The first sudden rise invacuum above the predetermined level causes the check valve 54 to closeand seal off the port 51. Air within the chamber 28 then flows throughthe restricted passage 60, thence into the peripheral groove 57, andthrough the aperture 58 to the port 51. In this manner, the chamber 28is evacuated over a period which is determined by the setting of thescrew 63. The level of vacuum within the chamber 28 eventuall rises to apoint where the dia sufficient y to move the stem 31 endwlse t erequired distance to operate the microswitch 70. Microswitch 70 isopened when the leaf spring 78 swings towards the enclosure 27 adistance sufficient to allow the spring-pressed plunger 77 moveoutwardly so as to open said microswitch. Thus, the timing device 10opens the circuit 101 which previously had been closed by the switch'106and, in so doing, turns off the warning lights 102. It will be'notedthat once the valve 54 reopens, as occurs when intake manifold pressurerises to a level sufficient to overcome the pressure of the spring 55,the vacuum within the chamber 28 is relieved almost immediately throughthe passages 39. The switch 70 of the timing device is then returned toits normally closed position without delay so as not to interfere withany subsequent operation of the switch 106. Thus, the switch 106 willcontrol the circuit 102 during normal operation of the car and thetiming device 10 will come into operation only if intake manifoldpressure is maintained at a predetermined high level for a selectedlength of time.

As previously mentioned, the solenoid 86 is energized the moment switch106 is closed. This serves to snap the stopper pad 92 against the casingwall25 so as to close off the vent 84. The timing device 10 thenoperates as above described without atmospheric air entering the vacuumchamber 28. As soon as the switch 106 is reopened, the circuit 101 isbroken and the solenoid 86 is deenergized to open the vent 84 and allowatmospheric air to flow into the vacuum chamber 28. This air is trappedwithin the vacuum chamber 28 the next time the solenoid 86 is energizedand it is the controlled flow of this air through the restricted passage60 which sets the time interval for the reopening of the circuit 101. I

From the foregoing it will be apparent we have provided a timing devicewhich will operate accurately even if the level of vacuum at the sourceis only slightly above the level required to actuate the device. Such acondition could cause the device 10 to operate prematurely but, byproviding the casing 24 with the vent 84 and said device with thecontrol means 16 for closing said vent at the appropriate moment, thereis no likelihood of the present timing device interfering with thenormal operation of the circuit in which it is connected. The timedinterval set for the opening of the microswitch 70 always remains thesame regardless'of the speed of the engine immediately prior to themoment when the rear warning lights are turned on.

We claim:

l. A timing device comprising a casing having a vacuum chamber, adiaphragm mounted in the casing to seal off one end of the vacuumchamber, switch means included in an electric circuit, means operativelyconnecting the diaphragm to the switch means, said casing having a portconnecting the vacuum chamber to a source of vacuum, a check valvemounted in the casing to open and close the port, said check valveclosing the port in response to a predetermined level of vacuum at thesource, said casing having a restricted passage connecting the vacuumchamber to the port and a vent normally open to atmosphere, and controlmeans in the electric circuit adapted to be actuated by energization ofsaid circuit to close the vent whereby the vacuum chamber is evacuatedthrough the restricted passage and over a selected period of time at theend of which the diaphragm is flexed and the switch means is actuated.

2. A timing device as claimed in claim 1, in which said control meanscomprises a solenoid connected into the electric circuit, an armaturemounted on the solenoid to extend alongside the casing, and a stopperpad on the free end of the arm to close the normally open vent.

hragm 30 will flex

1. A timing device comprising a casing having a vacuum chamber, adiaphragm mounted in the casing to seal off one end of the vacuumchamber, switch means included in an electric circuit, means operativelyconnecting the diaphragm to the switch means, said casing having a portconnecting the vacuum chamber to a source of vacuum, a check valvemounted in the casing to open and close the port, said check valveclosing the port in response to a predetermined level of vacuum at thesource, said casing having a restricted passage connecting the vacuumchamber to the port and a vent normally open to atmosphere, and controlmeans in the electric circuit adapted to be actuated by energization ofsaid circuit to close the vent whereby the vacuum chamber is evacuatedthrough the restricted passage and over a selected period of time at theend of which the diaphragm is flexed and the switch means is actuated.2. A timing device as claimed in claim 1, in which said control meanscomprises a solenoid connected into the electric circuit, an armaturemounted on the solenoid to extend alongside the casing, and a stopperpad on the free end of the arm to close the normally open vent.